Man, it takes years to build this useful life skills.

Indeed it does.

I've always been fearful of what lies behind the door. I stay outside thinking about the possibilities that lie on the other side instead of just knocking it down and getting in.

Life is a corridor of doors and only by finding the courage to enter some of them can we understand what may lie on the others side, good or bad. Failures will happen, but success will too...Provided one overcomes the fear of taking the first step.

I did read one personal development book that introduced me to the concept of 'no thoughts, just actions!'

Most PD books have something of value in them. I'm not sure if I'd endorse no thought as evaluation, strategy and planning has worked well for me*, although yes, overthinking it, then giving into fear and becoming immobile isn't going to move a person forward.

It sounds like you're on the right track.